Product packaging material and its manufacturing method

ABSTRACT

This invention relates to a product packaging material and method, and in particular to a product packaging material (27) formed from a length of rolled corrugated paper (20) and a method of manufacture therefor. There is provided a packaging material comprising corrugated paper (20), the corrugated paper including non-sinusoidal corrugations (16, 18, 72). There is also provided a method of making a packaging material of multi-layer corrugated paper (27) including the steps of forming corrugated paper (20) having a sheet with sinusoidal corrugations (42), and compressing the sheet to destroy the sinusoidal form of at least some of the corrugations.

FIELD OF THE INVENTION

This invention relates to a product packaging material and method, andin particular to a product packaging material formed from a length ofrolled corrugated paper and a method of manufacture therefor.

BACKGROUND TO THE INVENTION

Many products need to be stored and/or transported in packagingmaterials selected to provide impact cushioning.

Environmental concerns today are resulting in the buyers, specifiersand/or designers of packaging products demanding cushioning materialsthat have as small an effect as possible on diminishing fossil fuelreserves and on increasingly overloaded landfill waste disposal sites;consequently materials manufactured from recycled waste materials, andwhich are themselves recyclable, are increasingly demanded.

Corrugated paper meets the requirement for a recyclable packagingmaterial, which often can also be re-used. Typically "single-faced"corrugated paper is used i.e. with a planar paper sheet having affixedto one side a sinusoidal corrugated sheet. Corrugated board is alsoavailable i.e. with the sinusoidal corrugated sheet sandwiched betweentwo planar sheets. Often the corrugated paper is used in multi-layerform. Corrugated paper is not however usually recommended for cushioningapplications such as may be required for the packaging of highly fragileproducts such as certain optical instruments and computer floppy discdrives.

DISCLOSURE OF THE PRIOR ART

Polyethylene foams are known for packaging optical equipment andcomputer floppy disc drives. This material is however petroleum based,using scarce and unrenewable resources. After use it is difficult todiscard in a manner of little detriment to the environment; often it issimply buried.

Paper, being wood based, can be recycled. Corrugated paper is usuallymade from recycled waste paper, and is also itself recyclable. Thecorrugated paper can be formed into a variety of suitable shapes; therequired form imposed by the manufacturer can be retained (at leastuntil the formed product is ready for use by the packager) by the use ofa suitable adhesive.

SUMMARY OF THE INVENTION

The applicants have sought to modify the properties of corrugated paper,single-faced or board, and when in multi-layer form, to permit its useas a material with increased cushioning properties.

As one feature of the invention the applicants therefore provide amodified corrugated paper, in which the corrugations are no longersinusoidal. Usefully the corrugations are of a crushed or tilted form,though they are still present i.e. the "crushing" is not so severe as toflatten the corrugations in the finished (marketed) material, but issufficiently severe to remove (destroy) the inherent strength of thesinusoidal form of the corrugations.

The applicants developed the invention from the realisation that theinternal fibrous structure of the material from which the corrugatedpaper is formed provides the resilience needed for restoring thecorrugated paper after an impact, so that it is ready to withstandanother impact; yet recognised also that the sinusoidal form into whichthe material is traditionally corrugated has too high a deformationmodulus i.e. it does not yield or deform sufficiently under low forceapplications, and so acts effectively as a "solid wall" against which apackaged product is required to "bounce", rather than as a cushion ableto absorb product movements (and being resilient also to return to ornearly to its original condition after absorbing an impact).

Delicate instruments in particular need to be gently cushioned, with thepackaging material (a) of a structure to yield to absorb an impact and(b) of a composition to return towards its original condition.

Thus according to a further feature of the invention we provide aproduct packaging material comprising corrugated paper, the corrugatedpaper including non-sinusoidal corrugations.

According to another feature of the invention we provide a method ofmaking a packaging material which includes the steps of formingcorrugated paper having a sheet with sinusoidal corrugations, anddeforming the corrugations to destroy the sinusoidal form. Thecorrugations can be deformed prior to the corrugated paper being formedinto the shape required of the packaging material, or can be deformedafter the corrugated paper has been so formed.

Conveniently the corrugated paper has the corrugated sheet adhered to abase sheet so that the separation between the corrugations ispre-determined, and then the corrugations are alternatively tilted toone side by the compressive force, or have their apices flattened.

According to yet another feature of the invention we propose a method ofmaking a cushioning material which includes providing a corrugated sheetwith non-sinusoidal corrugations, and adhering the sheet to a basesheet, whereby to provide compressed corrugated paper. If manufacturedutilising conventional machinery, with this method the corrugated sheetwill first be made with sinusoidal corrugations, which thereafter aredeformed, as by being passed between nip rollers or placed in a press.

The applicants have found that such modified ("deformed") corrugationsretain the material resilience and restoration needed for productprotection against repeated impacts (as over long journeys or underother vibration conditions), but that the deformed, non-sinusoidal,corrugations deflect more readily at lower applied forces, with enhancedcushioning. Typically the packaging material will be used in multi-layerform, and so for applications with anticipated high vibration or impactloading, the packaging materials will conveniently have more than onelayer of compressed corrugated paper, though a deeper corrugation canalternatively be used to provide such "thicker" packaging material.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a section of part of a sheet of single-faced corrugated paperaccording to the invention;

FIG. 2 is a side view of corrugated paper wound into a multi-layer roll;

FIG. 3 is a side view of the roll of FIG. 2, having been flattened;

FIG. 4 is a side view of the flattened roll of FIG. 3, having been cutinto blocks;

FIG. 5 is a view of a block of FIG. 4, having been compressed into amulti-layer product packaging material according to the invention;

FIG. 6 is of a multi-layer packaging material, shaped to accommodate acorner edge of a product to be transported;

FIG. 7 is a view of a pair of nip rollers used to deform the sinusoidalcorrugations of the corrugated paper;

FIG. 8 is a view of a press having deformed the corrugations of amulti-layer product packaging material;

FIG. 9 is an exploded view of another embodiment of multi-layer productpackaging material; and

FIG. 10 is a section of part of an alternative embodiment of sheet ofsingle-faced corrugated paper.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, a paper-based sheet 10 is of generally planar section, andhas attached thereto at positions 12, as by adhesive, a similar sheet 14but formed into corrugations 16,18. Thus, there is provided a sheet ofsingle-faced corrugated paper 20. In this embodiment the corrugations16,18 have been deformed (as by the nip rollers 40 of FIG. 4), and as aresult the corrugation 16 has been tilted so that its apex 17 is nolonger in the median plane between the points, lines, or positions ofadhesion 12, whilst the corrugation 18 has been generally crushed i.e.its apex has been flattened and its wall portions 13 deformed, andpartially crushed.

In other embodiments, all of the corrugations on a single sheet aredeformed similarly i.e. all of the corrugations are crushed, or all ofthe corrugations are tilted. In yet another embodiment, the form of thedeformed corrugations is random.

In an alternative known embodiment, the apices of the corrugations canbe adhered to a second planar sheet, with the corrugations sandwichedtherefore between two planar sheets, to form corrugated board.

For use as a packaging or cushioning material, the corrugated paper willbe wound or laminated into multi-layer form in conventional manner.

A single-faced sheet of corrugated paper has glue painted upon theapices of the corrugations, and is then wound (around a mandrel) uponitself to produce a wound roll 22; thereafter the roll is retained in a"forming" machine until the adhesive sets, whereby to provide therequired final shape of packaging material, in this embodiment aflattened roll 24 (FIG. 3). The flattened roll 24 is then cut to lengthto provide one or more blocks of packaging material 26 (FIG. 4), whichblocks are then compressed (as by a press 50 of FIG. 8), to deform thecorrugations and produce a block 27 of packaging material (FIG. 5).

It will be understood that since the corrugated paper is wound uponitself (in this embodiment as a double coil or winding), that thecorrugations 28a,b of the innermost winding of the roll become enmeshed,i.e. as viewed in FIG. 5 the lower two sheet portions have thecorrugations upwards whilst the upper two sheet portions have thecorrugations downwards.

In this embodiment the roll 22 is formed into a packaging materialhaving four layers of over-laid single-faced corrugated paper, wherebyto provide the packaging material, though in other embodiments a greateror lesser number of over-laid layers can be utilised.

In the alternative embodiment of FIG. 6, the roll is formed into an "L"section corner piece 30, suitable for protecting the corners of anarticle to be transported. This corner piece could likewise be formedfrom adhering two of blocks 22 at 90° to each other.

Other suitable shapes of packaging material may be provided, either "asformed", or by combining blocks of suitable shape.

In the embodiment of FIG. 1, the sheet is compressed i.e. thecorrugations are deformed prior to forming the multi-layer packagingmaterial. This may be achieved by a pair of nip rollers 40 as shown inFIG. 7. Thus, after the corrugated sheet 14 has been adhered to theplanar sheet 10 in conventional manner, the sheet of single-facedcorrugated paper 20 is passed between rollers 40, which are spaced apartby less than the height of the (undeformed) sinusoidal corrugations 42.Upon passing between the rollers 40, the corrugations become deformed,either to the crushed condition 18, or the tilted condition 16, of FIG.1, or to a random combination of these conditions. The degree ofcompression can be determined by the spacing of the rollers 40, whilstthe deformation of the corrugations can in part be determined by therate of rotation of the rollers 40 relative to the permitted speed ofpass of the sheet 20.

In the embodiment of FIG. 5 the corrugations have been deformed bycompression only after the packaging material has been formed to shape.As shown in FIG. 8, already formed product packaging material 27 ofknown type is placed beneath a reciprocating press 50, shown returningfrom a compression step. It will be understood that prior to theengagement of the press, the corrugations in the packaging material hadbeen sinusoidal, but after being compressed by the press, they are inthe deformed condition such as that of FIG. 5.

Whilst in FIG. 5 all of the formed layers 52,53 and 54 are showndeformed, the pressure applied by press 50 is arranged preferentially todeform only the corrugations of the inner layer(s) 53 i.e. rather thanthe corrugations of the outer layer(s). Likewise, in a product packagingmaterial formed from a sheet 10 of FIG. 1, it may be arranged that notall of the corrugations be defomed prior to roll winding, e.g. theportion of the corrugated sheet which will make up the outer layers ofthe block of packaging material is not passed through nip rollers 40,whilst the portion of the corrugated sheet which will make up the innerlayers is passed through nip rollers.

Alternatively, different degrees of compression, and thus of corrugationdeformation, may be applied to different portions of the sheet, as byvarying the gap between the nip rollers 40 as the sheet passestherethrough, or by compressing a formed block with a curved, orotherwise non-flat, press.

The degree of compression used will affect the properties of the productpackaging material. Furthermore, the thickness of the paper from whichthe corrugations are formed, the size and spacing of the corrugations,the number of layers of corrugated sheet used, as well as the degree ofcompression can all be varied to determine the properties of thefinished material and packaging product.

In the further alternative embodiment of FIG. 9 (exploded view), flatprepared sheets of corrugated paper 60 of predetermined size and shapeare adhered together in a stack providing the multi-layer packagingmaterial 62. In this embodiment the corrugations of adjacent pieces ofcorrugated paper are arranged to run perpendicular to those of adjacentlayers, but in an alternative embodiment they can run parallel. It willbe understood that the corrugations in this embodiment can be deformedprior to adhering the sheets into a stack (as in FIG. 1), or thepackaging material 62 may be compressed, as by a press 50 of FIG. 8,after the sheets have been adhered together. A single planar sheet 64 isadded to the upper layer (as viewed) of corrugations so that the productpackaging piece presents a flat surface on its top and bottom surfaces,though in some situations the planar sheet 64 will not be required.

The sheet of corrugated paper 70 of the embodiment of FIG. 10 isproduced on a non-standard corrugating roller, so that the form of thecorrugated paper sheet 72 as manufactured is non-sinusoidal, and hasin-built i.e. pre-formed deformations or shoulders 74, which in use actwe believe to allow preferential compression of the corrugated paper ifunder reduced loading. Thus, the corrugated paper 70 will have a lowerresistance to compression than paper with sinusoidal corrugations.

The corrugated paper 70 may be formed into a packaging material by thewinding process discussed in relation to FIG. 2, or by the layeringprocess discussed in relation to FIG. 6. A packaging material so madehas been found to have improved cushioning capabilities over materialmade with standard (sinusoidally) corrugated paper. The corrugated paper70, and any packaging material made therefrom, does not require asubsequent or separate compression process to achieve the improvedcushioning properties.

It will be understood that other embodiments, having different forms ofirregular corrugations, can also be developed to provide the requiredcushioning properties.

It has been found that the packaging material is particularly effectivefor light but bulky products, having a low static loading upon thepackaging material. In one example, a packaging material comprisingtwenty four layers of corrugated paper was fully compressed, i.e. all ofthe corrugations were deformed to a flat condition throughout thematerial; the resilience of the material caused it to spring back to athickness of approximately 45 mm, and the material was then found toprovide maximum cushioning protection in a 300 mm drop for a staticloading of between 0.015 kg/cm² and 0.03 kg/cm².

Furthermore, tests have suggested that if a product is to be subjectedto "normal" transit conditions (i.e. to mail order drop testspecifications or general materials handling specifications), apackaging material 40 mm thick (comprising twenty layers of corrugatedpaper, which material has been fully compressed) will be required toprovide sufficient cushioning. Clearly, however, where the conditions ofuse can be better controlled, the thickness required may be less than 40mm.

I claim:
 1. A method of making a packaging material comprising the stepsof (i) forming a sheet of corrugated paper having sinusoidalcorrugations, (ii) deforming at least some of the corrugations todestroy their sinusoidal form, (iii) applying adhesive to apices of thecorrugations of the sheet of corrugated paper; (iv) winding the sheetinto a roll to form a multi-layer material; (v) pressing the roll ofmaterial into a shaped material condition; and (vi) permitting theadhesive to set whereby to retain the material in the said shapedcondition.
 2. The method according to claim 1 further comprising anadditional step of cutting a section of the shaped material into apackaging block.
 3. The method according to claim 1 further comprisingan additional step of adhering a planar sheet of paper to the sheet ofpaper having sinusoidal corrugations prior to the step of deforming atleast some of the corrugations.
 4. A method of making a packagingmaterial comprising the steps of (i) forming a sheet of corrugated paperhaving sinusoidal corrugations, (ii) applying adhesive to apices of thecorrugations of the sheet of corrugated paper; (iii) winding the sheetinto a roll to form a multi-layer material; (iv) pressing the roll ofmaterial into a shaped material condition; (v) permitting the adhesiveto set whereby to retain the material in the said shaped condition; and(vi) passing the shaped material through a press whereby to deform atleast some of the corrugations to destroy their sinusoidal form.
 5. Themethod according to claim 4 in which at least one paper-engagement faceof the press is non-planar.
 6. The method according to claim 4comprising an additional step of cutting a section of the shapedmaterial into a packaging block.
 7. A method of making a packagingmaterial, comprising the steps of (i) forming a sheet of corrugatedpaper having corrugations of a pre-shouldered form, (ii) applyingadhesive to apices of the corrugations of the sheet of corrugated paper;(iii) winding the sheet into a roll to form a multi-layer material; (iv)pressing the roll of material into a shaped material condition; and (v)permitting the adhesive to sat whereby to retain the material in thesaid shaped condition.
 8. A method of making a packaging materialcomprising the steps of (i) securing a sheet of corrugated paper to asheet of plain paper, (ii) applying adhesive to the exposed apices ofthe corrugations of the sheet of corrugated paper, (iii) winding thesheet of corrugated paper and the sheet of plain paper into a roll toform a multi-layer material; (iv) pressing the roll of material into ashaped material condition; (v) permitting the adhesive to set whereby toretain the material in the said shaped condition; and (vi) passing thematerial through a press whereby to deform at least some of thecorrugations.